1. Field of the Invention
The present invention relates to surveillance camera systems, and more particularly to a rotary scanner for a surveillance camera for outdoor use that has water-resistant features to prevent rainwater and other moisture from entering the internal mechanics of the scanner, and which includes one or more magnetically operable positioning stops for setting the limits of the camera scan.
2. Description of the Prior Art
In the field of surveillance cameras, it is often desirable for the camera to be deployed with a housing that is mounted outdoors where it is exposed to changes in climate. It is also desirable for the camera housing to be mounted on a base that is part of an oscillating mechanical rotary unit that allows the camera to scan a particular area. Such rotary scanning units are typically mounted on top of a structure such as a protruding beam or a pole, but are also frequently mounted in an inverted position such as underneath a beam, as a dangling pendant, on a ceiling, and the like. When mounted on top of a structure, the camera housing tends to act as a shield, deflecting precipitation such as rain and snow away from the base. However, when mounted in an inverted position (such as underneath a ceiling or soffit), the underside of the housing and mounting base may be directly exposed to these elements. Over time, such exposure can result in rust and damage to mechanical parts, and, if the housing is penetrated, potential corrosion and damage to the camera and sensitive internal printed circuit boards.
It is therefore desirable to provide a housing and base assembly for a surveillance camera that is resistant to water and moisture penetration, especially when mounted in an inverted position, to provide protection for the internal electrical and mechanical components from exposure to precipitation, moisture and other external foreign contaminants.
Oscillating mechanical rotary bases are well known in the art, and have been used on surveillance cameras, household fans, and other devices for many years, allowing such devices to oscillate back and forth between defined limits. Such bases allow a surveillance camera to scan an area between the limits, instead of having a stationary view from being constantly pointed in the same direction. It is often desirable to be able to easily adjust the positions of the end limits or stops of the oscillation area in order to increase or decrease the size of the area to be scanned.
Existing scanning bases for surveillance cameras utilize one or physical switches inside the camera housing on the rotating part that are associated with adjustable mechanical stops on the stationary base which set the limits of the scan. The mechanical toggle lever of each switch extends out and away from the camera enclosure through a hole in the enclosure. When the rotating part approaches one of the stops, the toggle lever of the switch makes contact with the stop. As rotation continues, the lever is moved, toggling the switch. Circuitry inside the enclosure recognizes the toggle, and reverses the direction of the drive motor thereby reversing the direction of rotation. This rotation continues until the toggle lever encounters another stop, at which point the stop again physically moves the lever, toggling the switch and reversing the direction of rotation. This back and forth rotation continues between the stops. The positions of the stops establish the beginning and ending points of the scanning arc (i.e. the length of the arc of rotation).
Unfortunately, the opening(s) in the camera enclosure required by the mechanical toggle lever of the switch(es) expose the internal circuitry to the outside atmosphere, and particularly to foreign material such as moisture and dust. Over time, exposure to such foreign material can and often does result in corrosion of the sensitive printed circuit boards, as well as rust and damage to other internal electrical and/or mechanical parts. In addition, over time, the switch lever(s) and contacts tend to wear out as a result of the constant back and forth physical contact of the switch lever(s) and the stop(s). These kinds of continuing failures result in the need to regularly repair or replace significant parts of the rotatable base and/or camera electronics.
U.S. Pat. No. 4,543,609 discloses a television surveillance camera system that employs a magnet attached to the camera and a set of magnetically sensitive position sensors deployed in fixed positions below the rotational arc of the camera for monitoring and changing the direction of rotation of the camera. However, the position sensors of this invention are fixed, making it impossible to alter the length(s) of the arc(s) of rotation of the camera, or for the camera to rotate through a full 360° or more.
It is therefore desirable to provide a rotary base for a surveillance camera that provides a flexible and adjustable scanning range through a full 360° or more, while also providing protection for the internal electrical and mechanical components from exposure to outside foreign contaminants.